We checked our ETA against the ship's own: 2.8 h vs 32.8 h
Across 371 closed voyages to Rotterdam over the last 30 days, Port Flow's predicted ETA was off by 2.8 hours on average. The crew-broadcast ETA those same ships transmit was off by 32.8.
The news
Every tanker broadcasts an ETA in its AIS message — typed in by the crew. Desks lean on it for berth planning, demurrage and cargo timing, even though everyone knows it drifts.
We measured how far. For every voyage that actually closed at Rotterdam in the last 30 days, we compared two ETAs against the real arrival: ours, and the ship's own broadcast.
Mean absolute error, same 371 closed voyages, last 30 days:
What it implies
On a single voyage that's the difference between holding a berth slot and missing it — and between budgeting demurrage and eating it.
We're not asking you to take our word for it: the number is published and updates as voyages close. Check it yourself.
The line
We checked our predicted ETA against the ship's own broadcast ETA over 371 closed voyages at Rotterdam: 2.8 h average error vs 32.8 h. We publish the number, updated as voyages close. portflow.uk/precision
Both figures are mean absolute error on the same voyage set; broadcast ETAs more than 7 days off (AIS sentinel/placeholder values) are excluded from both. Public AIS, Rotterdam, 30-day window — snapshot dated 12 June 2026.
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